The present invention relates generally to hinge mechanisms for knee braces, and more particularly to an improved hinge system for a knee brace which is adapted to simulate the movements of a knee joint while regulating its flexion and extension within a plurality of prescribed ranges of motion.
A knee joint is essentially comprised of two joints, namely, lateral and medial joints, which are positioned between the femur and tibia. The primary movements of the knee joint are flexion (rearward rotational movement of the tibia relative to the femur) and extension (forward rotational movement of the tibia relative to the femur). The flexion and extension movements of the knee joint are not, however, limited to simple pivotal movements about a fixed axis.
Rather, the axis around which flexion of the knee joint occurs shifts backward, while shifting forward during extension thereof. This is different from other types of hinge joints such as elbow joints where the axes of rotation do not shift at all.
When the knee joint is fully extended, the tibia is rotated forward which in effect locks the joint in position with the ligaments taut. This tend to provide greater stability to the knee joint. Furthermore, when the knee joint begins to flex from the fully extended position, the tibia first is lowered with a small external rotation which unlocks the knee joint. Thereafter, the tibia rotates rearward about the knee joint to full flexion. In this regard, the initial unlocking of the knee joint during flexion proceeds actual full rotation of the knee.
Because of the complexity associated with knee movement as described above, a knee brace hinge mechanism must be able to simulate the movements of the knee than a simple hinge. The incorporation of such hinge mechanism is important as the knee brace must optimally support the knee joint of its user. For instance, in the context of post-surgical applications, the requirement for such simulation of the knee joint is essential in order to properly rehabilitate and/or prevent re-injury of an injured knee joint. In addition to this requirement for such post-surgical applications, the hinge mechanism should also be able to control the range of knee joint flexion and extension so that the joint does not re-injure itself due to hyper-extension and/or flexion. As the optimal range of knee joint motion may vary between users and/or change during the progress of rehabilitation, the knee brace hinge mechanism used in conjunction with such surgical applications should further be adjustable to correspond to the particular motion range of the user's leg.
In recognizing the need for an effective post-surgical knee brace, various types of hinge mechanisms have been incorporated into currently available knee braces for post-surgical applications. However, most conventional hinge mechanisms typically fail to provide the precise simulation of knee joint movement as described above or control the range of knee joint motion. Such deficiency inevitably decreases the likelihood of the user's knee joint from being properly rehabilitated after surgery. Further, most contemporary knee brace hinge mechanisms typically fail to possess sufficient adjustability so as to quickly and easily provide the optimal set range of knee motion depending upon the current user's needs and/or rehabilitation progress.
In view of the above-described shortcomings of conventional knee brace hinge mechanisms, there exists a substantial need in the art for a hinge system that can closely simulate the motion of the knee joint while regulating the range of its flexion and extension. More specifically, there exists a substantial need for a hinge system which can be easily and quickly adjusted so as to provide a variable, optimal range of knee joint flexion and extension for the particular need of its user.